Seal ring and method

ABSTRACT

A seal ring  10  for sealing between first and second members  12, 14  each having an outer groove surface  16, 126  and inner groove surface  18, 127  includes a metal seal body  26, 42, 52, 60, 70, 80, 92, 110, 122, 140  for engagement with the outer groove surface on the first and second members, and a metal flexible flange  30, 32, 44, 46, 54, 56, 62, 64, 76, 78, 88, 90, 94, 96, 112, 114, 128, 144, 146  with a cantilevered end of a flexible flange providing substantially line contact sealing engagement with the inner groove surface on respective first and second member. The metal flexible flange is configured for being fluid pressure energized, and is deformed beyond its elastic limit when securing members secure the first member to the second member.

FIELD OF THE INVENTION

This invention relates to seal rings of a type for sealing between firstand second members each having a throughbore, such as flanges, clamps,and hub type connectors. More particularly, this invention relates to aseal ring which is pressure energized within the groove receiving thesealing ring, thereby maintaining sealing integrity even if the securingbolts between the first and second members elongate to permit flangeseparation.

BACKGROUND OF THE INVENTION

Pressure vessels are conventionally composed of structural sectionshaving flanges or other connectors at their extreme ends. The flangesare secured to the assembly by securing bolts that extend through themating flanges. The opposed flanges may be drawn together about a metalsealing ring with sufficient force to cause metal-to-metal sealingbetween surfaces on the seal ring and tapered surfaces on the opposingseal grooves in the first and second members.

An API seal ring may leak under circumstances where the bolts areproperly tightened to secure the flanges in sealed engagement, butthereafter excessive heat causes bolt extension such that the flangesare allowed to be moved apart a slight amount. When this occurs, theremay be insufficient mechanical force between the seal ring and themating wall surfaces of the seal groove to maintain a fluid tight seal.Also, when the flange bolts are made up very tightly, metal coiningbetween the seal ring and the mating wall surfaces may occur, in whichcase only a slight movement of the flanges may cause seal leakage.Coining of the seal ring typically occurs, because the seal ring metalis less hard than the metal defining the receiving grooves in theflange. Overstressing the studs to shut off a leak may also causecoining of the seal ring groove. It is frequently recommended to employperiodic tightening of flange bolts to prevent leaking in hightemperature applications.

U.S. Pat. No. 4,410,186 discloses a seal ring for flanged joints, andwas part of a seal concept for nuclear reactor applications. Due to widetolerances, an API seal ring groove would be coined by this type of sealring. To eliminate coining, one would have to make several sizes of aseal ring for a specific ring groove. This type of seal ring also wouldnot seem suitable for holding pressures at high temperatures when thestuds elongate because of its limited flexibility.

U.S. Pat. No. 5,058,906 discloses a seal ring formed from a highstrength material. For the seal ring to function, the ring flexesagainst the ring groove wall to burnish and form a seal. The seal ringis intended to flex within its elastic limits, and again would requirenumerous different seal rings to work satisfactorily within a single APIring groove.

U.S. Pat. No. 5,240,263 discloses a seal ring with a substantial uniformcross sectional thickness. The patent teaches substantially planarcontact between surfaces of the seal ring and the tapered surfacesdefining the seal groove. This type of seal may leak because there is nopressure energization. Because the seal areas are large, pressure canmigrate into the seal area thus equalizing pressure, resulting inleakage.

The disadvantages of the prior art are overcome by the presentinvention, and an improved seal ring and method are hereinafterdisclosed for reliable sealing between two members.

SUMMARY OF THE INVENTION

In one embodiment, a seal ring for sealing between first and secondmembers each having an outer groove surface and an inner groove surfaceincludes a metal seal body for engagement with each of the radiallyoutward surfaces on the first and second members when the securingmembers secure the first member to the second member. A metal flexibleflange radially inward of the seal body has a cantilevered end whichprovides substantially line contact sealing engagement with a respectiveinner groove surface, while a spacing or gap between the flexible flangeand the seal body provides for fluid pressure energization of theflexible flange. The flexible flange is deformed beyond its elasticrange when the securing members secure the first member to the secondmember.

In another embodiment, the seal ring includes a metal flexible flangesupported on the seal body and extending radially inward such that acantilevered end of a flexible flange provides substantially linecontact engagement with one of a groove base surface and an inner groovesurface on the respective first or second member. The flexible flange isdeformed beyond its elastic limit when the securing members secure thefirst member to the second member, and a spacing or gap between theflexible flange and the seal body provides for fluid pressureenergization of the flexible flange.

The seal ring as disclosed herein is able to maintain dynamic sealingintegrity even in the event of a fire. Due to plastic yielding and/ortelescoping, the shape of the seal is able to change while maintaininghigh sealing reliability.

These and further features and advantages of the present invention willbecome apparent from the following detailed description, whereinreference is made to the figures in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a side view of a seal ring according to the presentinvention for sealing between first and second members.

FIG. 2 illustrates in greater detail a cross section of the seal ringshown in FIG. 1.

FIG. 3A discloses an alternate embodiment of a seal ring, and FIG. 3Bdiscloses a seal ring as shown in FIG. 3A when the securing members havesecured the first member to the second member.

FIG. 4 discloses yet another embodiment of a seal ring wherein theflexible flanges are slidably movable relative to the seal body.

FIG. 5 discloses yet another embodiment of a seal ring.

FIGS. 6 and 7 disclose additional embodiments of a seal ring.

FIG. 8 discloses an embodiment of a seal ring with a radially extendingflexible flange.

FIG. 9 discloses a flexible flange slidably movable relative to a sealbody.

FIGS. 10A and 10B illustrate yet another embodiment of a seal ringwherein a pair of flexible flanges are shown in FIG. 10A supported on aseal ring before the securing members are tightened, and FIG. 10Billustrates the same sealing ring with the securing members tightened.

FIG. 11A depicts yet another embodiment of a seal ring prior to themember being secured to the second member, and FIG. 11B shows the sameseal ring with the first and second members secured.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates a seal ring 10 for sealing between first and secondmembers 12, 14 each having a respective throughbore 13, 15. Each member12, 14 has an outer tapered groove surface 16 directed radially inwardin a direction away from an interface between the members 12, 14, and aninner tapered groove surface 18 directed radially outward in a directionaway from the interface between members 12 and 14. A groove base 20 isshown spaced between the surfaces 16, 18, and is substantiallyperpendicular to a common axis 22 of the through bores. A plurality ofsecuring members 24, such as bolt and nut assemblies, are arrangedcircumferentially about the members 12, 14 and secure the first memberto the second member. In some applications, clamping devices or othertypes of flange connecting members may be used to rigidly secure thefirst member to a flange end of a second member. An annular grooveformed by the surfaces 16, 18, 20 is thus provided for receiving thesealing ring 10 therein.

Referring to FIG. 2, the sealing ring 10 comprises a metal seal body 26for engagement with the radially outer surface 16 on the first andsecond members when the securing members 24 secure the first member tothe second member. An annular flange 28 may be pressed on or otherwisesecured to the seal body 26, and is compressed between the surface 25 onthe body 12 and surface 27 on the body 14 when the bolts 24 aretightened. The sealing ring 10 further includes a pair of metal flexibleflanges 30, 32 each radially inward of the seal body 26, such that acantilevered end 31, 33 of each flexible flange provides substantiallyline contact sealing engagement with the inner tapered surface 18 on arespective first and second member 12, 14. A spacing 34, 36 between eachflexible flange and the seal body 26 provides for fluid pressureenergization of the flexible flange. As shown in FIG. 2, the spacing 34,36 includes a minimum spacing between a radially outward planar surfaceof the flexible flange and a radially inward planar surface of the metalseal body. This minimum spacing is substantially greater than a minimumthickness of the corresponding metal flexible flange. At least a portionof this minimum spacing is formed by an outer planar surface of theflexible flange and a corresponding inner planar surface of the metalseal body being substantially parallel surfaces. The cantilevered or tipend 31, 33 of each flange is thus forced radially inward into tightersealing engagement with a respective surface 18 in response to highpressure fluid in the bore of the members 12, 14.

For the embodiment as shown in FIG. 2, the seal body 26 and the flexibleflanges 30, 32 are formed from a unitary homogeneous material. In otherapplications discussed below, the annular flange 28 and the seal body 26may be formed from a unitary homogeneous material. The seal body 26 andthe pair of flanges 30, 32 as shown in FIG. 2 form a substantiallyC-shaped cross-sectional configuration, as shown in FIGS. 1 and 2.

FIG. 2 depicts in dashed lines the “as manufactured” configuration ofthe seal body and flexible flanges, and illustrates in solid lines thefinal position of the seal body and flexible flanges after the boltshave been tightened and before high pressure is applied to the seal ring10. There is a small angular mismatch between the radially outer taperedsurface 29 on the seal body 26 and the corresponding outer taperedsurface 16 on each of the members 12 and 14, with this mismatchresulting in a substantially line contact seal 38 between the seal bodyand the surfaces 16. Those skilled in the art appreciate that, inresponse to high fluid pressure within the bore, the mismatched surfaceson the seal body may be pressed outward into substantially planarengagement with the groove surfaces 26 on the first and second members,since the seal body deforms slightly in response to this high fluidpressure. Whether under high pressure or low pressure, the seal betweenthese components is effectively provided by line contact engagement,since even under high pressure, substantially higher sealing forces areexerted at point 38 than at other points along the radially outersurface 27 of the seal body. Thus even if high pressure results insubstantially planar contact between surfaces 27 and 16, substantiallyline contact metal-to-metal sealing is achieved at point 38.

Sealing effectiveness of the seal ring is not solely dependent upon boltloading, since the flexible flange of the seal ring is also pressureenergized. Also, the surface on the first and second member which issealingly engaged by a metal flexible flange preferably is not coined.The seal ring changes its shape to maintain seal integrity when opposingseal grooves move apart due to temperature changes or changes in theseal ring due to flexure or yielding, or by telescoping of the sealring, as explained further below. During substantial separation of thefirst and second members, the flanges may move axially apart 0.025inches or greater, yet seal integrity may be maintained at a highpressure. The seal maintains an effectiveness during flange separation,and is interchangeable with standard API and/or ANSI seal rings.

By including a flexible flange on the seal ring ID and an interferencefit on the seal ring OD, the installed flexible flange tip makes sealingcontact with a wall of the groove, while a corner of the OD of the sealring and/or an annular sealing bump on the OD of the seal ring contactsthe outside groove wall. When the flange bolts are tightened, theflexible flange is flexed outwardly while the OD of the seal ring isflexed inward, resulting in strengthened self-energization of the sealring. When internal pressure is applied to the seal ring, an additionalfluid pressure generated force is created on the flexible flange, whilesimultaneously an outward force is created on the seal body. These fluidpressure induced forces further strengthen the seal and establish apressure-energized seal. The seal ring maintains sealing integrityduring flange face separation since the inward flexure of the seal bodyand the outward flexure of the flexible flange stores energy in the sealring, acting in the manner of a spring. This stored energy is releasedwhen being supplemented by the internal fluid pressure within the firstand second members to maintain contact between the seal ring and thegroove walls during separation.

FIG. 3A depicts an alternate seal body 42 and a pair of metal flexibleflanges 44 and 46 with a spacing 48, 50 provided between each flexibleflange and the seal body 42. The seal body as shown in FIG. 3A does notinclude a annular flange, and accordingly the surface 25 on the member12 directly engages the surface 27 on the member 14 when the bolts aretightened, as shown in FIG. 3B.

FIG. 3B also depicts each flexible flange 44, 46 in substantially linecontact sealing engagement with the base surface 20 at point 45 on thecantilevered end of flanges 44 and 46. Again, the configuration of theseal body and flexible flanges in its “as manufactured” condition isshown in dashed lines in FIG. 3B, and is shown in solid lines in itsposition when the bolts are tightened. Other seal configurationsdiscussed below also show the “as manufactured” and “final” position,although only the final position is shown in some figures. All sealconfigurations are, however, deflected before obtaining the finalconfiguration. The end surface 45 forming a substantially line contactseal is thus similar to the end surface 31 shown in FIG. 2, except thatsealing engagement in the FIG. 3B embodiment is with the base surface 20rather than the inner groove surface 18. A mismatch between the angle ofthe surface 16 and the radially outward angled surfaces 43 on the sealbody 42 are depicted, with the body thus being configured forsubstantially line contact sealing engagement with each of the annularflanges.

Referring to FIG. 4, the seal body 52 is provided with an annular flange28. A mismatch between the outer surface 53 on body 52 and the taperedouter groove surface 16 results in line contact sealing engagement withthe members 12, 14 at sealing point 38. A pair of metal flexible flanges54 and 56 provide a line contact seal with the surfaces 18 on the firstand second members at point 31, while spacing 55, 57 between the metalflexible flanges 54, 56 and the seal body 52, and in this case betweenthe flexible flanges 54, 56 and the flange supporting component 58 ofeach flexible flange, provides fluid pressure energization of theflexible flange. The flange component 58 is slidable in a generallyaxial direction relative to the seal body 52, and the surfaces 59 on theflanges 54, 56 engage the base surface 20 of the groove in response tohigh fluid pressure, as shown. Again, the flexible flange is deformedbeyond its elastic range when the securing member secure the firstmember to the second member. Sealing between 58 and 52 is accomplishedby tapering one of the surfaces on 58 or 52 which engage the othercomponent, and/or by providing an annular bump or protrusion on one ofthese surfaces.

FIG. 5 depicts yet another embodiment of a seal ring, wherein the sealbody 60 is unitary and homogeneous with the annular flange 28. In thiscase, the seal body supports flexible end flanges 62 and 64 each open tofluid pressure energization by a respective gap 66 provided between thesurface 18 and the body 60. Spacings 63, 65 provide for fluid pressureenergization of the flexible flanges 62 and 64. Additional slots 67, 68and 69 are provided for increasing the flexibility of the end flanges62, 64, with slots 67 and 69 being directed substantially radiallyinward, and the slot 68 being directed substantially radially outward.The seal ring 60 seals at point 38 with the surface 16 as previouslyexplained, and the cantilevered end 31 of each flange member 62, 64thereby obtains substantially line contact sealing engagement with thesurface 18.

FIG. 6 depicts another embodiment on a metal seal body 70 having aradially outward flange 28 secured thereto. The seal body is intendedfor substantially line contact sealing engagement with the radiallyoutward surface of each member 12, 14, and accordingly annular bump 72is provided on the member 12 for substantially line contact sealingengagement with the seal body 70, while the mismatch of the anglesbetween the outer surface of the seal body and the radially outwardgroove wall 16 also may or may not provide line contact sealing at point73. As an alternative to providing the raised bump 72 on the member, asealing bump 74 may be provided on the seal body, as shown in FIG. 6. Apair of metal flexible flanges 76 and 78 are each configured forsubstantially line contact sealing engagement with the radially inwardtapered surface of the members 12, 14 at point 31. A spacing 77, 79 isprovided between each flexible flange and the seal body for fluidpressure energization of the flexible flanges. Each of the flexibleflanges 76, 78 is deformed beyond its elastic limit when the securingmembers secure the first member to the second member.

The embodiment in FIG. 7 illustrates an alternative seal body 80 whichis integral with the radially outward flange 28. Line contact sealingengagement with the member 12 is provided by the annular bump 82 on theseal body, and by the mismatch surfaces which may result in line contactsealing at point 84. FIG. 7 also depicts a bump 86 provided on the lowermember 14 for line contact sealing engagement with the seal body. Thepair of flexible flanges 88 and 90 include respective spacings 89 and 91for fluid pressure energization of the flexible flanges. Each flange 88,90 is thus pressure energized, and provides a substantially line contactseal with the groove surface 18 at point 31. If desired, one of thebumps on the seal body or on the member 12, 14, or one of the linecontact seals 84 created by angular mismatch, may be eliminated, sinceboth a primary and a backup seal with each member 12, 14 is shown inFIGS. 6 and 7.

FIG. 8 depicts yet another seal body 92 having a flange 28 securedthereto, with the seal body 92 supporting a pair of flexible flanges 94and 96 each configured for substantially line contact sealing engagementat 31 with the radially inner wall 18 of each body 12, 14. Asubstantially radially extending gap 95 and 97 is provided between andflexible flange and the seal body for fluid pressure energization ofeach flexible flange.

FIG. 9 depicts an alternative seal body 110 having a radially outwardflange 28 secured thereto. In this case, flange 114 is provided on theseal body for substantially line contact sealing engagement at 31 withthe tapered surface 18 on the lower member 14, with a groove 115provided between the flexible flange 114 and the body 110. A flange 112is provided on flange support 116, which is slidable in a substantiallyradial direction relative to the body 110. A bump 118 on the flangesupport 116 provides substantially line contact sealing engagement withthe body 110, while the mismatch between the outer surface of thesupport 116 and the inner surface of the body 110 provides forsubstantially line contact sealing engagement at 120. Spacing 113provides for fluid energization of the flexible flange 112. The body 110also seals with the members 12, 14 by line contact sealing of mismatchedangular surfaces, as previously discussed. Increased flexibility isprovided since flange 112 is axially movable relative to body 110.

FIG. 10A depicts yet another embodiment of a seal ring including a metalseal body 122 having a flange 28 integral therewith. An annular bump 124on the seal body is provided for sealing engagement with the radiallyoutward surface 126 of each member 12, 14. A pair of metal flexibleflanges 128 each include a support member 130 for slidable engagementwith the inner wall 132 of the body 122, and an annular bead or raisedsection 134 is provided for substantially line contact sealingengagement with the metal seal body. Each flange 128 includes an annularbead 136 for substantially line contact sealing engagement with theinner wall 138 of the groove. Shown in FIG. 10B, the seal ring sealswith each member 12, 14 by substantially line contact sealing engagementwith radially inward groove surface 138 at point 136 between the metalflexible flange and a respective member, by the seal 134 providedbetween each flange support member 130 and the metal seal body 122, andby annular bead 124 provided between the metal seal body and theradially outward groove wall 126 of the members 12, 14. The spacing 127between each flexible flange 128 and a respective support member 130provides for fluid pressure energization of the flexible flange. Eachflexible flange is axially movable relative to the body 122, so thataxial variations between the base surfaces 20 of the ring groove do nothave a significant adverse effect on sealing effectiveness.

FIG. 11A discloses another embodiment, wherein the seal body 140 has aflange 28 integral and homogeneous therewith. A mismatch between theouter surfaces on the flange body and the outer tapered groove surfaces16 on the members 12, 14 provides for substantially line contact sealingengagement between the seal body and the members at point 142, as shownin FIG. 11B. Surfaces 141 on body 140 may be tapered to facilitatesliding the base piece 143 on the seal body 140. Each seal body alsoincludes a pair of flexible flanges 144 and 146 each in contact with aninsert body 148. When assembled, line contact sealing engagement atpoint 31 is formed between each flange 144, 166 and the respective body12, 14. Protrusion 145 on each base piece 143 forms a line contact sealwith surface 141 on seal body 140. The spacing 147 between flexibleflanges 144 and 146 and the sliding base piece 143 is preferably filledwith a compressible material, as shown in FIG. 11A, such as anelastomer, a high temperature graphite, Teflon™, or a plastic. Basepiece 145 may be formed from metal, but alternatively may be a plasticmaterial component. When the bolts are tightened, the insert 148 iscompressed, resulting in the seal body shown in FIG. 11B.

According to the present invention, comparatively low preloading may beused to form an effective seal between the groove surfaces of the ANSIor API flange and the seal ring. An API or ANSI flange joint may havemismatched members, and the seal ring groove surface diameters may varyby ±0.032 or more. The seal ring may be pressure energized by theinternal pressure within the first and second members to maintain aneffective seal.

An API or ANSI seal ring material may have a yield strength of 30,000psi or less. The seal ring will thus only stretch 0.001 inches or lessper inch of diameter. If the yield strength of the seal ring gasket isincreased to 60,000 psi or greater, the seal ring as well as the groovewalls may be permanently deformed. The seal ring is sufficientlyflexible that the internal pressure will flex the seal ring and make ityield under applications of use, such as flange separation at hightemperature. One seal ring may be made to fit one size groove without aproblem because of a flexure, yielding, and telescoping capabilities ofthe seal ring, without the sealing surface being coined and preferablyonly burnished at the point of sealing contact.

The seal ring is highly interchangeable since the seal ring fits into astandard API and/or ANSI seal ring groove. The features of the seal ringare realized when the flange joint is assembled according to recommendedpractices.

In a room temperature test on a 2 1/16th inch, 5,000 psi API flangeconnection with a seal ring according to the present invention, theflange joint was made up finger tight on the bolts, yet the connectionheld sealing integrity at 100 psi at 70° F. Pressure was subsequentlyincreased to 10,000 psi, and was maintained for 24 hours withoutleakage.

In a fire test, flanges made from A105 carbon steel, 2 inch size, Class300 with B7 studs were torqued to 125 pounds. The API classification forthis flange is Class F, meaning that the flange should leak under therequirements of the test. During the test, the upper flange reached atemperature of 1225° F. and the lower flange temperature was 1265° F.and the stud temperature reached 1250° F. Sealing integrity wasmaintained with no leakage, and the flange was subjected to a connectiontest of 555 psi. As the test equipment cooled down to 72° F.measurements of the stud showed that they averaged 0.010 inch permanentelongation due to high stud torque applied to the studs. The fluidinternal pressure does not exert enough separation load on the flange tomake the studs yield at this temperature.

It should be understood that the terms “line contact seal” or“substantially line contact sealing” mean that sealing engagementbetween the metal components is provided by substantially alignedcontact engagement, e.g., of a metal flexible flange with one of thefirst and second members. Such line contact sealing engagement issignificantly more effective at sealing than substantialplanar-to-planar engagement of metal surfaces. Substantially linecontact engagement may nevertheless result from sealing engagement ofsurfaces over a short length, so that the forces resulting in sealingare concentrated along a small surface area.

Each of the embodiments disclosed herein provides for a relatively thinflexible flange which is responsive to high fluid pressure within theinterior of the members 12, 14 to increase sealing effectiveness. Eachflexible flange is thus forced into tighter sealing engagement with therespective member when fluid pressure increases. Each flexible flange isalso deformed from its original as manufactured condition to a sealingposition in which at least part of the seal ring is deformed beyond itselastic limit when securing members secure the first member to thesecond member.

The seal disclosed herein may be used in API or ANSI flange ring groovesand other special ring grooves, and will maintain seal integrity withvery low restraining load, such as stud load, even if the flangesseparate a small amount in a fire and the studs elongate in response toa temperature of up to about 1200° F. The seals are especially sensitiveto leakage with flange separation. For example, for every 0.001″ offlange separation, a prior art seal may lose 0.001″ squeeze in each ringgroove, and if the seal shifts, the seal may lose 0.002″ squeeze andleak. Any movement on standard seals will leak. For the seal asdisclosed herein to work in these types of grooves, it forms a dynamicseal that changes its shape as the gland formed by the two ring grooveschanges shape, and the seal is pressure energized. The seal design isthus based on flexure, instead of rigidity and high compression loadingcommon for standard seals.

The metal seal body disclosed herein is designed so that it changesshape by flexing, yielding and/or telescoping. Because the seal body canchange shape these three ways, shape changes such as thermal expansionand contraction can practically be ignored.

The pressure energized metal seal achieves high sealing with a pressuremultiplier designed into the seal. This feature creates a substantiallygreater force per square inch between the seal ring and the ring groovethan the internal pressure on the seal body causing this force. If theinternal pressure of 1000 psi acts on 10 square inches and the sealengages the groove at only 0.5 square inches, the force acting on theseal to force sealing engagement is 20,000 pounds.

Although specific embodiments of the invention have been describedherein in some detail, this has been done solely for the purposes ofexplaining the various aspects of the invention, and is not intended tolimit the scope of the invention as defined in the claims which follow.Those skilled in the art will understand that the embodiment shown anddescribed is exemplary, and various other substitutions, alterations andmodifications, including but not limited to those design alternativesspecifically discussed herein, may be made in the practice of theinvention without departing from its scope.

1. A seal ring sealing between first and second members each having athrough bore, the seal ring and first and second members comprising:each first and second member having a radially outer circumferentialgroove surface inclined outwardly in a direction toward the seal ring,and a radially inner circumferential groove surface inclined inwardly ina direction toward the seal ring; securing members arrangedcircumferentially about the first and second members to secure the firstmember to the second member; and a seal ring including a metal seal bodyhaving a yield strength of 30,000 psi or less engaging each of the outergroove surfaces on the first and second members when the securingmembers secure the first member to the second member, the metal sealbody having a radially inward facing body surface spaced axially betweenan uppermost body surface and a lowermost body surface, the metal sealbody being flexed inward when the securing members are moved to securethe first member to the second member, and a metal flexible flangeradially inward at the seal body such that a cantilevered end of theflexible flange provides substantially line contact sealing engagementwith the inner groove surface on a respective first and second member, aspacing between the flexible flange and the seal body projectingradially outward of the inward facing body surface to increaseflexibility of the flange and providing for fluid pressure energizationof the flexible flange, the spacing including a minimum spacing betweena radially outward planar surface on the flexible flange and a radiallyinward planar surface on the metal seal body, the minimum spacing beinggreater than a maximum thickness of the metal flexible flange, and theflexible flange flexed outwardly and being deformed beyond its elasticrange when the securing members secure the first member to the secondmember.
 2. A seal ring and first and second members as defined in claim1, wherein the seal body and the flexible flange are formed from aunitary homogenous material.
 3. A seal ring and first and second membersas defined in claim 1, wherein the seal body has substantially linecontact sealing engagement with the outer groove surface on a respectivefirst and second member.
 4. A seal ring and first and second members asdefined in claim 1, further comprising: an annular flange extendingradially outward from the seal body for planar engagement with planarflange engaging faces on the first and second members.
 5. A seal ringand first and second members as defined in claim 1, wherein the sealbody and another flexible flange forms a substantially C-shaped crosssectional configuration.
 6. A seal ring and first and second members asdefined in claim 5, wherein a spacing between each of the pair offlexible flanges and the seal body is substantially filled with anelastomer, such that fluid pressure on the elastomer exerts increasingsealing pressure between each flexible flange and the inner groovesurface on a respective first and second member.
 7. A seal ring andfirst and second members as defined in claim 1, wherein the flexibleflange is fixedly secured to the seal body.
 8. A seal ring and first andsecond members as defined in claim 1, wherein a slidable membersupporting the flexible flange is axially movable relative to the sealbody; and a substantially line contact seal between the slidable memberand the seal body.
 9. A seal ring and first and second members asdefined in claim 1, wherein the outer groove surface is a taperedsurface directed radially inward in a direction away from an interfaceof the first and second members, and the inner groove surface is atapered surface directed radially outward in a direction away from theinterface of the first and second members.
 10. A seal ring and first andsecond members as defined in claim 1, further comprising: anotherflexible flange for substantially line contact sealing engagement withthe other of the first and second members.
 11. A seal ring sealingbetween first and second members each having a through bore, the sealring and first and second members comprising: each first and secondmember having a radially outer circumferential groove surface inclinedoutwardly in a direction toward the seal ring, a radially innercircumferential groove surface, and a circumferential base surfacebetween a respective outer groove surface and inner groove surfaceinclined inwardly in a direction toward the seal ring; securing membersarranged circumferentially about the first and second members to securethe first member to the second member; and a seal ring including a metalseal body having a yield strength of 30,000 psi or less engaging each ofthe outer groove surfaces on the first and second members when thesecuring members secure the first member to the second member, the metalseal body having a radially inward facing body surface spaced axiallybetween an uppermost body surface and a lowermost body surface, themetal seal body being flexed inward when the securing members are movedto secure the first member to the second member, and a metal flexibleflange radially inward at the seal body such that a cantilevered end ofthe flexible flange provides substantially line contact sealingengagement with the inner groove surface on a respective first andsecond member, a spacing between the flexible flange and the seal bodyprojecting radially outward of the inward facing body surface toincrease flexibility of the flange and providing for fluid pressureenergization of the flexible flange, the spacing including a minimumspacing between a radially outward planar surface on the flexible flangeand a radially inward planar surface on the metal seal body, the minimumspacing being greater than a maximum thickness of the metal flexibleflange, and the flexible flange flexed outwardly and being deformedbeyond its elastic range when the securing members secure the firstmember to the second member.
 12. A seal ring and first and secondmembers as defined in claim 11, wherein the seal body has substantiallyline contact sealing engagement with the outer groove surface on arespective first and second member.
 13. A seal ring and first and secondmembers as defined in claim 11, wherein the cantilever end of theflexible flange is in sealing engagement with the base of a respectivefirst and second member when the securing members secure the firstmember to the second member.
 14. A seal ring and first and secondmembers as defined in claim 11, wherein the cantilevered end of theflexible flange is in sealing engagement with the inner groove surfaceof a respective first and second member when the securing members securethe first member to the second member.
 15. A seal ring and first andsecond members as defined in claim 11, wherein the outer groove surfaceis a tapered surface directed radially inward in a direction away froman interface at the first and second members, and the inner groovesurface is a tapered surface directed radially outward in a directionaway from the interface of the first and second members.
 16. A seal ringand first and second members as defined in claim 11, further comprising:one or more radially extending slots in the seal body for increasingflexibility of the flexible flange in response to fluid pressure.
 17. Aseal ring sealing between first and second members each having a throughbore in fluid communication with the throughbore in the other member,the seal ring and first and second members comprising: each first andsecond member having a circumferential mating surface extending radiallyoutward from the respective throughbore and a circumferential groove inthe mating surface open to the circumferential groove in the othermember and having a radially outer circumferential groove surfaceinclined outwardly in a direction toward the seal ring, a radially innercircumferential groove surface inclined inwardly in a direction towardthe seal ring, and a circumferential base surface between a respectiveouter groove surface and inner groove surface, the outer groove surfacebeing a tapered surface directed radially inward in a direction awayfrom an interface of the first and second members, and the inner groovesurface being a tapered surface directed radially outward in a directionaway from the interface of the first and second members; securingmembers arranged circumferentially about the first and second members tosecure the first member to the second member; the seal ring including ametal seal body having a yield strength of 30,000 psi or less engagingeach of the outer groove surface on the first and second members whenthe securing members secure the first member to the second member, themetal seal body having a radially inward facing body surface spacedaxially between an uppermost body surface and a lowermost body surface,the metal seal body being flexed inward when the securing members aremoved to secure the first member to the second member, a pair of metalflexible flanges supported on to the seal body and each extendingradially inward such that a cantilevered end of a flexible flangeprovides substantially line contact engagement with one of the basesurface and the inward groove surface on a respective first and secondmember, the seal body and the pair of metal flexible flange having asubstantially C-shaped cross-sectional configuration, and each flexibleflange being deformed beyond its elastic limit when the securing memberssecure the first member to the second member, and a substantiallyradially extending spacing between the flexible flange and seal bodyprojecting radially outward of the inward facing body surface toincrease flexibility of the flange and providing for fluid pressureenergization of the flexible flange.
 18. A seal ring and first andsecond members as defined in claim 17, wherein a radially outer portionof the seal body is thicker than a thickness of either of the pair ofmetal flexible flanges.
 19. A seal ring and first and second members asdefined in claim 17, wherein each of the pair of metal flexible flangesextends axially toward each other.
 20. A seal ring and first and secondmembers as defined in claim 17, wherein the cantilevered end of eachflexible flange is in sealing engagement with the inner groove surfaceof a respective first and second member when the securing members securethe first member to the second member.
 21. A seal ring and first andsecond members as defined in claim 17, wherein a spacing between each ofthe pair of flexible flanges and the seal body is substantially filledwith an elastomer, such that fluid pressure on the elastomer exertsincreasing sealing pressure between each flexible flange and the innergroove surface on a respective first and second member.
 22. A seal ringand first and second members as defined in claim 17, wherein the minimumspacing between the radially outward planar surface on the flexibleflange and the radially inward planar surface on the metal seal body isgreater than an axial thickness of the metal flexible flange between anend of the spacing between the flexible flange and the seal body and arespective upper more surface or lower more surface on the respectivemetal flexible flange.